I've merged your two related posts into one. Now, let's see what we can do to get you up and running with 1Password on your iPhone!

The most common cause of Master Password discrepancies between devices is having multiple separate vaults. For example, you might have a standalone vault on your Mac, the Master Password of which you are using there, and be trying to sign in to a 1Password account on your iPhone. If you have an account with us and see a Primary vault in 1Password on your iMac, that's probably the culprit; you might want to finish migrating to a 1Password account if what I've described sounds like your issue.

Otherwise, you could be typing the Master Password incorrectly for one of many reasons. Our Forgot Master Password guide here has helpful tips to help you get your Master Password entered correctly in the 1Password app.

Let me know how those suggestions help and I'll be here for more for you. We can also take this conversation to email, grab some under-the-hood diagnostics from 1Password on your devices, and see if that lets us identify the culprit.